Team Alberta Emphasizes Water, Local Materials: Solar Decathlon

To see how the newest innovations in solar power and energy efficiency can be incorporated into homes, we headed down to the Solar Decathlon on the National Mall in Washington, D.C. The competition, run by the Department of Energy (and sponsored in part by Popular Mechanics), pits 20 college teams against one another in a showdown of architecture and engineering.

The SolAbode built by Team Alberta, made up of students from four schools in Calgary, reflects the forested, mountainous and sometimes industrial environment of southern Alberta. The exposed wood post-and-beam construction features reclaimed barnwood and spruce timbers from a community forest in British Columbia; part of the facade and the core of the house is covered by rundlestone from Canmore, and another part of the facade is covered by rusted corten steel--a nod to Canada's oil industry.

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The team also acknowledged the rivers connecting various ecosystems with a heavy emphasis on water systems. A 500-gallon tank acts as a heat source for the home's water-to-water heat pump, which heats and cools the home through a forced air system, and a 1500-gallon tank acts as a heat sink. That's where energy is deposited when cooling the house--it's then rejected through thermosyphons to the outside air at night. Both tanks are concealed in wooden compartments on the deck.

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"The contest puts a premium on electricity and the heat pump is a big electrical draw," says Mike Gestwick, a graduate student in environmental design at the University of Calgary. So the system was designed to operate at its highest efficiency: Flat-plate solar thermal collectors, which are mounted vertically on the southern facade, are connected to the heat source tank. Fluid from the collectors deposits heat in the tank, so that the temperature of the water approaching the heat pump is already high. Conversely, the solar thermal system operates at its most efficient when the approach fluid is cooler, which it is after circulating back from the thermal storage tank. "These are on-the-shelf components," Gestwick says. "What's innovative is how we put them together."

The home's mechanical closet is located on the upper deck--a unique feature for a Solar Decathlon home--and accessing it requires walking past the 7.6-kilowatt solar array, made up of 37 modules from Sanyo. Because this can throw shading on one or two panels, the team chose to use microinverters so that each module converts electricity from DC to AC independently; with a centralized inverter, the performance of the entire system could be comprised.

A closet inside the home contains a programmable logic controller typically used in industrial systems. "It's kind of overkill," Gestwick says, "but we wanted to do more than typical home automation." The technology monitors the energy performance of the home, ensuring that it operates at maximum efficiency. It can also control the pumps for heating and cooling using temperature sensors located throughout the house. The students wrote a program that allows residents to quickly execute different control scenarios.

Gestwick describes the Solar Decathlon project as "incredible--and a challenge. What we've done is basically start a small business." Besides designing and building an actual house, the student-led process included fundraising, marketing and communications. "A lot more than just engineering," Gestwick says. For him, the experience has solidified his interest in energy analysis in a built environment: "What better way to learn than to go out and do it?"

People who miss Team Alberta's house at the Solar Decathlon this weekend can tour it at the 2010 Winter Olympics in Vancouver.